Hybrid simulation of wake-vortex evolution during landing on flat terrain and with plate line

Wake-vortex evolution during approach and landing of a long range aircraft is investigated. The simulations cover final approach, touchdown on the tarmac, and the evolution of the wake after touchdown. The wake is initialized using a high fidelity Reynolds-averaged Navier-Stokes solution of the flow field around an aircraft model. The aircraft in high-lift configuration with deployed flaps and slats is swept through a ground fixed domain. The further development of the vortical wake is investigated by large-eddy simulation until final decay. The results show the formation of a pronounced shear layer at the ground and an increase in circulation in ground proximity, caused by the wing in ground effect. Disturbances at disconnected vortex ends, so-called end effects, appear after touchdown and propagate along the wake vortices against the flight direction. They lead to a circulation decay of the rolled-up wake vortices, combined with a growth of the core radius to 300% of its initial value. After touchdown wake vortices are subjected to strong three-dimensional deformations and linkings with the ground. The complete vortex evolution, including roll-up and decay, is accelerated in ground proximity. Additionally the effect of a plate line installed in front of the runway is studied with this method. The plates cause disturbances of the vortices propagating to either side and interacting with the end effects. The plate line further accelerates the vortex decay, reducing the circulation rapidly by another 25% of its initial value.